Re: first display on twinview
This isn't really a bug. More of a feature that needs to be added.
If you use KDE (I don't really use Gnome) you can set everything to the monitor you want using the KDE settings, which support Xinerama very well. I'm sure GNOME is the same way.
You can also modify gmd.conf to change the display GDM displays on. I'm sure KDM can do the same thing.